Markey Pathway Course in Heart Failure

Hypertrophy of cardiac muscle is a fundamental response to any condition that causes the heart to work harder. It can arise from a pressure overload state (e.g., systemic hypertension or aortic stenosis), a volume overload state (e.g., mitral or aortic regurgitation), a state in which substantial ventricular muscle has been lost to infarcts and the remaining muscle must do more work, or conditions in which the muscle itself has been injured directly and cannot pump blood to meet metabolic demands without undergoing some compensatory changes. In hypertrophy, sarcomeres can be added both in series and in parallel orientations depending, in part, on the extent of ventricular dilatation that may also occur. Much progress has been made in identifying chemical and mechanical signals, receptors for these signals, and signal transduction pathways that mediate the hypertrophic response. These include stretch, 1-adrenergic pathways, and pathways activated by various growth factors including angiotensinII, endothelin, and growth hormone.